1 terror, alarm, fear, fright, dread, horror, dismay, consternation, hysteria; anxiety, apprehension, apprehensiveness, nervousness:
As the speeding car veered towards us, a feeling of panic gripped me.
2 be terrified or alarmed or fearful or frightened or terror-stricken or terror-struck, dread, fear, lose one's nerve; frighten, scare; Colloq go to pieces, fall apart, Brit lose one's bottle:
I panicked, turned the wheel the wrong way, and crashed the car into a tree. Gregory panics at the slightest sign of danger
3 frighten, scare, alarm, terrify, unnerve:
Something panicked the horses and one kicked out his stall door.